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What’s the Matter
Chemistry is the study of matter and the transformations it can
undergo…
Chemistry is the study of matter and the transformations it can
undergo…
…. Matter is anything that occupies space.
Guiding QuestionsWhy do substances boil or freeze at different temperatures? Why do we put salt on the roads in the winter?
What properties of diamonds make them useful in a variety of applications?
Classification of Matter
• Scientists classify or group materials based on different characteristics. Matter can be classified according to whether it is a mixture or a pure substance.
MATTER
Can it be physically separated?
Homogeneous Mixture
(solution)
Heterogeneous Mixture Compound Element
MIXTURE PURE SUBSTANCE
yes no
Can it be chemically decomposed?
noyesIs the composition uniform?
noyes
Colloids Suspensions
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Particle Theory of Matter
• All matter is made up of tiny particles
• Each pure substance has its own kind of particle, which is different from the particles of other pure substances.
• Particles attract each other• Particles are always moving.• Particles at a higher
temperature move faster, on average, than particles at a lower temperature.
Cl-
ions
Na+
ions Water molecules
Pure Substances
• Contain only one kind of particle.
• e.g. water, oxygen gas, chlorine gas, sodium metal.
• Can be classified into two main groups: elements and compounds. Sulphur on the left is composed of one type
of atom, and water on the right is made up of a compound, with 1 type of molecule (2 hydrogen and 1 oxygen atom).
Pure Substances
Element– composed of identical atoms– EX: copper wire, aluminum foil
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Pure Substances
Compound
– composed of 2 or more elements in a fixed ratio
– properties differ from those of individual elements
– EX: table salt (NaCl)
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Pure Substances
Law of Definite CompositionLaw of Definite Composition
– A given compound always contains the same, fixed ratio of elements.
Law of Multiple ProportionsLaw of Multiple Proportions
– Elements can combine in different ratios to form different compounds.
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Pure Substances
For example…
Two different compounds, each has a definite composition.
Carbon, C Oxygen, O Carbon monoxide, CO
Carbon, C Oxygen, O Oxygen, O Carbon dioxide, CO2
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Elements – A Pure Substance
• Cannot be broken down further by chemical or physical methods.
• Elements are organized into the periodic table based on similar properties.
Copper is an element – a pure substance
Compounds – A Pure Substance
• Is made of two or more different elements that are chemically compound.
• Water is a compound made of the elements hydrogen and oxygen.
• Can be broken down into its elements by chemical methods.
• Water can be broken down into hydrogen and oxygen by electrolysis.
+
-- + -+
Sodium Chloride NaCl – a compound (Salt)
Mixtures
• Contain more than one kind of particle.
• Salt water is a mixture of salt dissolved in water.
• Air is a mixture of gases that include nitrogen, oxygen and carbon dioxide. A granite rock is a
heterogeneous mixture. Notice the different visible parts (minerals).
Mixtures
Variable combination of two or more pure substances. Contain more than one particle.
Heterogeneous Homogeneous
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Mixtures
Solution– homogeneous– very small particles
– particles don’t settle– EX: rubbing alcohol
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Mixtures
Colloid– heterogeneous– medium-sized particles– particles don’t settle– EX: milk
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Mixtures
Suspension– heterogeneous– large particles– particles settle– EX: fresh-squeezed
lemonade
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Matter Flowchart
Examples:
– graphite
– pepper
– sugar (sucrose)
– paint
– soda
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element
heterogenous mixture
compound
solution Homogenous mixture
heterogenous mixture
Mixtures
Examples:
– mayonnaise
– muddy water
– fog
– saltwater
– Italian salad dressing
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colloid
suspension
colloid
solution
suspension
Classification of Matter
Materials
HomogeneousHeterogeneous
Heterogeneousmixture
Homogeneousmixture
Substance
Element Compound Solution Mixture
Speci
fic /
Gen
eral
Order / Disorder
Smoot, Smith, Price, Chemistry A Modern Course, 1990, page 43
Classification of Matter
MATTER(gas. Liquid,
solid, plasma)
PURESUBSTANCES MIXTURES
HETEROGENEOUSMIXTURE
HOMOGENEOUSMIXTURESELEMENTSCOMPOUNDS
Separated by
physical means into
Separated by
chemical means into
Kotz & Treichel, Chemistry & Chemical Reactivity, 3rd Edition , 1996, page 31
Elements, Compounds, and Mixtures
(a)an element(hydrogen)
(b)a compound(water)
(c)a mixture(hydrogen and oxygen)
(d)a mixture(hydrogenand oxygen)
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 68
hydrogenatoms hydrogen
atoms
oxygen atoms
Elements, Compounds, and Mixtures
(a)an element(hydrogen)
(b)a compound(water)
(c)a mixture(hydrogen and oxygen)
(d)a mixture(hydrogenand oxygen)
Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 68
hydrogenatoms hydrogen
atoms
oxygen atoms
Mixture vs. Compound
Mixture
FixedComposition
Bonds between
components
Can ONLY beseparated by
chemical means
VariableComposition
No bondsbetween
components
Can beseparated by
physical means
Alike Different
Contain two or more
elements
Can beseparated
intoelements
Involvesubstances
Compound
Different
Topic Topic
Compounds vs. Mixtures
• Compounds have properties that are uniquely different from the elements from which they are made. – A formula can always be written for a compound
– e.g. NaCl Na + Cl2
• Mixtures retain their individual properties.– e.g. Salt water is salty and wet
Separating Mixtures
• A filter can separate solids from liquids or gases.
• Distillation can separate liquids in a mixture based on boiling point by vapourization, condensation.
• Magnets will attract iron and steel objects.
Methods of Separating Mixtures
• Magnet
• Filter
• Decant
• Evaporation
• Centrifuge
• Chromatography
• Distillation
Filtration separates
a liquid from a solid
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40
Mixture ofsolid andliquid Stirring
rod
Filtrate (liquidcomponentof the mixture)
Filter papertraps solid
Funnel
Chromatography
• Tie-dye t-shirt
• Black pen ink
• DNA testing– Tomb of Unknown Soldiers– Crime scene – Paternity testing
Setup to heat a solution
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 42
Ring stand
Beaker
Wire gauze
Ring
Bunsen burner
A Distillation Apparatus
liquid with a soliddissolved in it
thermometer
condenser
tube
distillingflask
pure liquid
receiving flaskhose connected to
cold water faucetDorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 282
The solution is boiled and steam is driven off.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 39
Salt remains after all water is boiled off.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 39
No chemical change occurs when salt water is distilled.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40
Saltwater solution(homogeneous mixture)
Distillation(physical method)
Salt
Pure water
Separation of a sand-saltwater mixture.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 40
Separation of Sand from Salt1. Gently break up your salt-crusted sand with a plastic spoon.
Follow this flowchart to make a complete separation.
Salt-crusted
sand.
Dry
sand.
Wetsand.
Weigh themixture.
Decant clearliquid.
Evaporateto
dryness.
Pour intoheat-resistant
container.
Fill with water.
Stir and letsettle 1 minute.
Weighsand.
Calculateweight of
salt.
Repeat3 times?
Yes
No
2. How does this flowchart insure a completeseparation?
Centrifugation
• Spin sample very rapidly: denser materials go to bottom (outside)
• Separate blood into serum and plasma– Serum (clear)– Plasma (contains red blood
cells ‘RBCs’)• Check for anemia (lack of iron)
Blood
RBC’s
Serum
A B C
AFTER
Before
The decomposition of two water molecules.
2 H2O O2 + 2 H2
Electriccurrent
Watermolecules
Diatomic Diatomicoxygen molecule hydrogen molecules+
Electrolysis
*Must add acid catalyst to conduct electricity
*H1+
water oxygen hydrogen
“electro” = electricity “lysis” = to split
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 32
Water
Hydrogengas forms
Oxygengas forms
ElectrodeSource ofdirect current
H2O(l) O2 (g) + 2 H2 (g)
Electrolysis of Water
Half reaction at the cathode (reduction): 4 H2O + 4 e - 2 H2 + 4 OH 1-
Half reaction at the anode (oxidation): 2 H2O O2 + 4 H 1+ + 4 e -
hydrogengas
cathode
oxygengas
anode
D.C. powersource
water
Advantages and Disadvantages
• Elements and compounds have positive effects on society such as making our lives healthier and safer.
• Negative consequences – toxic chemicals that are used to produce in the manufacture or isolation of certain elements and compounds can be released into the environment and cause bioaccumulation.
Frog with three legs due to chemical exposure.
ELEMENTELEMENT
hydrogen molecule, H2
ELEMENTELEMENT
oxygen molecule, O2
MIXTUREMIXTURE
a mixture ofhydrogen and oxygen molecules
CHEMICAL REACTIONCHEMICAL REACTION
if molecules collide with enoughforce to break them into atoms, a can take place
COMPOUNDCOMPOUND
water, H2O
2 H22 H2 O2
O2 2 H2O2 H2O++ ++ EE
Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
The Zeppelin LZ 129 Hindenburg catching fire on May 6, 1937 at Lakehurst Naval Air Station in New Jersey.
S.S. Hindenburg
35 people died when the Hindenburg exploded.
May 1937 at Lakehurst, New Jersey
• German zeppelin luxury liner
• Exploded on maiden voyage
• Filled with hydrogen gas
Reviewing ConceptsReviewing ConceptsClassifying Matter
• Why does every sample of a given substance have the same properties?
• Explain why the composition of an element is fixed.
• Describe the composition of a compound.• Why can the properties of a mixture vary?• On what basis can mixtures be classified as
solutions, suspensions, or colloids?• Name two processes used to separate
mixtures?